The invention relates to a loading device for kneaders, screw-type extruding machines or the like, having at least one feed chute and at least one tamping tool, the feed chute being provided with at least one load opening.
In the known loading devices of the above-named type for kneaders, a rectangular or round plunger is moved linearly up and down in a rectangular or round loading chute. The plunger is secured to a plunger rod and is guided by the rod. The loading chute has an opening that can be sealed by means of a flap and that permits horizontal filling (EP 0,272,338).
The known loading devices for kneaders have considerable drawbacks. For example, the height of the known loading devices is several times greater than the actual required plunger stroke. Moreover, the flexural and torsional strengths of the plunger rod stipulated by its large length/diameter ratio are not sufficient to guide the plunger in a defined manner without contact with the loading chute. The resulting wear of the known loading devices has a consequence, although minor, of contamination of the mixed material by material particles. In addition, the plunger is constantly twisted in the loading chute during the mixing process, and knocks against the loading chute. This can result in a fatigue fracture in the cooling water lines and damage to the chute plates. Furthermore, when recipes are changed the mixer must be cleaned frequently in order to prevent contamination of the subsequent mixture. Because it is very difficult to gain access to the upper region of the known loading devices, lengthy cleaning times and subsequently long machine down times result.
The object of the known loading devices of the above type for screw-type extruding machines as tamping mechanisms is to present the caoutchouc material that results in irregular form to the barrel extruder and generating a pressing force in the caoutchouc so that the caoutchouc material is drawn into the extruder evenly and with high efficiency. The loading devices are configured as linear tamping tools and encompass two rectangular, hydraulically linearly moved tamping tool plungers disposed radially to the screw-type extruding machine, of which plungers the one, as the secondary tamping tool, presents the caoutchouc material to the barrel extruder and the other, as the main tamping tool, applies the radial pressing force to draw in the material.
The known loading devices for screw-type extruding machines are relatively expensive in production, require a large amount of space, and cause considerable problems with respect to cleaning and maintenance. In addition, because of the force relationships that result during operation, they require a holding mechanism that leads to large, interfering sealing gaps.